Stable aqueous epoxy resin dispersion, process for the preparation thereof and use thereof

ABSTRACT

The invention relates to stable epoxy resin dispersions and also a process for the preparation thereof and the use thereof, in particular for coatings. The epoxy resin dispersions which are remarkable, in particular, for good storage stability with a low content of organic solvents at the same time and yield coatings with good surface properties, contain, in addition to water, optionally small quantities of organic solvents and also optionally usual additives, epoxy resin hardeners and the like, as an essential constituent a condensation product of 
     (a) 50 to 80% by weight of an epoxy compound containing at least two epoxy groups per molecule and having an epoxy equivalent of 100 to 2,000, 
     (b) 35 to 17% by weight of an aromatic polyol and 
     (c) 15 to 3% by weight of a condensation product of an aliphatic polyol with a molecular weight (Mw) of 200 to 20,000 and an epoxy compound containing at least two epoxy groups per molecule and having an epoxy equivalent of 100 to 2,000, the equivalent ratio of the OH groups to the epoxy groups being 1:0.85 to 1:3.5 and the epoxy equivalent of said condensation product being between 200 and at least 50,000.

It is known that synthetic resins are prepared by emulsionpolymerisation and stable aqueous dispersion of said resins are producedby adding the solid resin and a suitable dispersant to water whilestirring. In the case of condensates such as epoxy resins, which aredifficult to prepare by emulsion condensation, aqueous dispersions must,however, be prepared by dispersing the solid resin in water. Suchdispersions are in general fairly unstable and sediment even in thecourse of a short time. They also generally exhibit fairly poorfilm-forming properties. These disadvantages, namely low stability ofthe dispersion and poor film properties, are mainly due to the largeparticle size of the resin. In the case of dispersions of solid resinsformed in the conventional manner, the mean particle size of the resinis in the order of magnitude of 50 μm or greater.

The preparation of coating compounds based on polyepoxide dispersions isdisclosed in the U.S. Pat. No. 3,772,228, according to which ahot-curing single-component coating compound is produced by grinding anddispersing a solid brittle polyepoxide, a solid brittle epoxy hardener,for example a polyanhydride, and also optionally an epoxide curingaccelerator in a liquid which is not a solvent for the variouscomponents. In this connection, aliphatic hydrocarbons are preferred. Inthis manner, epoxy resin dispersions are obtained which are not,however, aqueous and which entail the risks inherent in the use ofhydrocarbon solvents.

The preparation of stable aqueous, organic-solvent-free dispersions ofepoxy resins of relatively low molecular weight (200 to 4,000,preferably 240 to 1,300) with mean particle sizes of less than about 10μm using anion-active nonionogenic, preferably, however, cation-activedispersants is also known (U.S. Pat. No. 3,879,324). In this case, theepoxy resin is heated to form a melt, mixed with water and thedispersant and then passed through a colloid mill. Only those epoxyresins with the specified molecular weight which melt below 100° C., theboiling point of water, can be dispersed by this process. This strictlimitation has the disadvantage that it excludes numerous useful epoxyresin systems of high molecular weight. Apart from that, dispersion atthe boiling point of water still yields relatively large particles whichrapidly sediment.

The preparation of epoxy solid resins which can also be obtainedimmediately in the form of an aqueous dispersion has also already beendescribed (U.S. Pat. No. 4,122,067). In that case block polymerscomposed of ethylene oxide and polypropylene glycol or polymers composedof polyethylene glycols with a molecular weight of 2,000 to 20,000 andpolyglycidyl ethers of polyphenols with a molecular weight of 300 to2,000 in a molar ratio of 2:1 to 6:5 are employed as dispersant. By thisprocess, too, only dispersions with a particle size of 1 to 3 μm areobtained.

According to the European Patent 81,163, polyalkylene glycol derivativesare employed as nonionic dispersants for stable aqueous epoxy resindispersions, mean particle sizes of less than 1 μm being possible. Thecoatings obtainable with these dispersions are still not, however, fullysatisfactory in a number of properties.

According to European Published Specification 0,051,483, epoxy resindispersions are obtained from self-emulsifying epoxy resins whichcontain polyoxyalkylene glycol glycidyl ether and optionally also amonoepoxide as reactive thinner. Approx. 3 μm is specified as maximumparticle size. Films which are prepared from these dispersions andhardeners have a relatively soft surface due to the content ofpolyoxyalkylene glycol glycidyl ethers, which are very inert, andoptionally monoepoxides which act as chain stoppers.

The object of the present invention was therefore to provide aqueousepoxy resin dispersions which have a high measure of stability with aslow a content of organic solvent as possible and from which coatings andthermosetting materials can be obtained which exhibit improvedproperties.

This object is achieved according to the invention by an aqueousdispersion based on a self-emulsifying epoxy resin (A), the dispersioncontaining, in addition to water (B), optionally up to 15% by weight,referred to the total dispersion, of organic solvents (C) and optionallynormal additives, hardener or further thermosetting resins (D), whereinthe self-emulsifying epoxy resin (A) has an epoxy equivalent of between250 and 10,000 and is a condensation product of

(a) 50 to 80, preferably 55 to 70% by weight of an epoxy compoundcontaining at least two epoxy groups per molecule and having an epoxyequivalent of 100 to 2,000,

(b) 35 to 17, preferably 35 to 20% by weight of an aromatic polyol and

(c) 15 to 3, preferably 9 to 4, % by weight of a condensation product ofan aliphatic polyol with a mean molecular weight (Mw) of 200 to 20,000and an epoxy compound containing at least two epoxy groups per moleculeand having an epoxy equivalent of 100 to 2,000, the equivalent ratio ofthe OH groups to the epoxy groups being 1:0.85 to 1:3.5 and the epoxyequivalent of said condensation product being between 200 and at least50,000.

Preferably, in the condensation product (c), the equivalent ratio of theOH groups to the epoxy groups is either (c₁) 1:0.85 to 1:1.5, inparticular 1:0.95 to 1:1.20 and the epoxy equivalent at least 100,000,or (c₂) the equivalent ratio is 1:1.8 to 1:3.5, in particular 1:2.0 to1:2.6 and the epoxy equivalent is between 400 and 10,000.

The invention further relates to a process for the preparation of saidepoxy resin dispersions, wherein the self-emulsifying epoxy resin (A) isfirst prepared by condensation of the three components A(a), A(b) andA(c) at elevated temperatures in the presence of a condensation catalystand optionally of organic solvents (C), optionally further organicsolvents (C) are subsequently added and then appropriate quantities ofwater and also optionally the compounds corresponding to (D) are addedat 30° to 100° C. with vigorous stirring to the solution so obtained.

Finally, the invention also has as subject the use of said epoxy resindispersions for the preparation of painting materials, coatings, moldingcompounds and thermosetting materials.

The self-emulsifying epoxy resin corresponding to (A) of the dispersionaccording to the invention has preferably an epoxy equivalent of 350 to2,500, in particular of 450 to 1,500. The mean particle size of thedispersed resin is, as a rule, not greater than 1.0 μm and is preferably0.25 to 0.8 μm, most preferably 0.3 to 0.8 μm. The proportion of saidresin in the total dispersion is in general about 20 to 70% by weight,preferably 25 to 55% by weight.

The 1,2-epoxy compounds corresponding to A(a) and A(c) are polyepoxideswith on average at least two epoxy groups per molecule. Said epoxycompounds may, at the same time be both saturated and also unsaturated,and also aliphatic, cycloaliphatic, aromatic or heterocyclic and mayalso contain hydroxyl groups. They may furthermore contain thosesubstituents which, under the mixing or reaction conditions, cause nointerfering side reactions, for example alkyl or aryl substituents,ether groupings and the like.

Preferably, these epoxy compounds are polyglycidyl ethers based onpolyhydric, preferably dihydric alcohols, phenols, hydrogenationproducts of said phenols and/or novolaks (reaction products of mono- ordihydric phenols with aldehyde, in particular formaldehyde, in thepresence of acidic catalysts). The epoxy equivalents of said epoxycompounds are preferably between 160 and 500, in particular between 170and 250. As polyhydric phenols, mention may be made, for example, of:resorcin, hydroquinone, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A),isomeric mixtures of dihydroxydiphenylmethane (bisphenol F),tetrabromobisphenol A, 4,4'-dihydroxydiphenylcyclohexane,4,4'-dihydroxy-3,3'-dimethyldiphenylpropane, 4,4'-dihydroxydiphenyl,4,4'-dihydroxybenzophenol, bis(4-hydroxyphenyl)-1,1-ethane,bis(4-hydroxyphenyl)-1,1-isobutane,bis(4-hydroxy-tert-butylphenyl)-2,2-propane,bis(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene,tris(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl) ether,bis(4-hydroxyphenyl)sulfone etc., and also the chlorination andbromination products of the abovementioned compounds. Bisphenol A isparticularly preferred in this connection.

The polyglycidyl ethers of polyhydric alcohols are also suitable. Asexamples of such polyhydric alcohols, mention may be made of ethyleneglycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,polyoxypropylene glycols (n=1-10), 1,3-propylene glycol, 1,4-butyleneglycol, 1,5-pentanediol, 1,6-hexanediol, 1,2,6-hexanetriol, glycerol andbis(4-hydroxycyclohexyl)-2,2-propane.

It is also possible to use polyglycidyl esters of polycarboxylic acidswhich are obtained by a reaction of epichlorohydrin or similar epoxycompounds which an aliphatic, cycloaliphatic or aromatic polycarboxylicacid, such as oxalic acid, succinic acid, adipic acid, glutaric acid,phthalic acid, terephthalic acid, hexahydrophthalic acid,2,6-naphthalenedecarboxylic acid and dimerised linolenic acid. Examplesare diglycidyl adipate, diglycidyl phthalate and diglycidylhexahydrophthalate.

A detailed enumeration of the suitable epoxy compounds is to be found inthe handbook entitled "Epoxidverbindungen und Epoxidharze [EpoxyCompounds and Epoxy Resins]" by A. M. Paquin, Springer Verlag, Berlin1958, chapter IV, and in Lee and Neville "Handbook of Epoxy Resins",1967, chapter 2. Mixtures of several epoxy compounds may also be used.

The aromatic compounds containing OH groups are preferable as aromaticpolyols corresponding to A(b) as described in the case of the componentsA(a) and A(c), i.e. polyhydric, preferably dihydric, phenols, theirchlorination or bromination products, and/or novalaks. Here, too,bisphenol A is also particularly preferred.

The aliphatic polyols of component A(c) are preferably polyether polyols(polyalkylene glycols) having mean molecular weights (Mw; gel permeationchromatography; polystyrene standard) of preferably 600 to 12,000, inparticular 2,000 to 8,000, and OH numbers expediently of 10 to 200,preferably 15 to 16. Said polyether polyols have preferably onlyterminal, primary OH groups. For example, mention may be made here ofblock copolymers of ethylene oxide and propylene oxide, and also ofpolyethylene, polypropylene and polybutylene glycols, it also beingpossible to employ mixtures of the respective polyalkylene glycols.Preferably, polyethylene glycols are used.

The condensation products A(c) may be obtained, for example, bycondensation of the said polyether polyols with the glycidyl ethers inthe presence of, for example, the following specific catalysts (c₁) atelevated temperature, in particular at 50 to 200, preferably 90° to 150°C.:

Boron trifluoride and its complexes, for example with water, phosphoricacid, acetic acid (1:1 and 1:2), methanol, diethyl ether,tetrahydrofuran, phenol, tricresyl phosphate, ethylene glycol monoethylether, polyethylene glycol (MG 200) dimethyl sulfoxide, di-n-butylether,di-n-hexyl ether and succinic acid or tetrafluoroboric acid in aqueousor organic solution. Lewis acids with different bases, such as SnCl₄,are, however, also suitable. Of these catalysts, BF₃ -diethyl ether, BF₃-acetic acid and tetrafluoroboric acid are preferably employed. Thequantity of catalyst is in general 0.1 to 5, preferably 0.15 to 1% byweight, referred to the reaction mixture. To improve the dosing, thecatalyst may be diluted in a solvent such as diethyl ether, a glycolether or cyclic ether, ketones or the like, preferably dioxane or methylisobutyl ketone in an amount of up to 0.5 to 20, preferably 2.5 to 12.5%by weight.

In this connection, the two components are employed in quantities suchthat the equivalent ratio of OH groups to the epoxy groups is in general1:0.85 to 1:1.15, preferably 1:0.95 to 1:1.20.

Preferred condensation products (dispersants) A(c) are those of theepoxy compounds described above, in particular polyglycidyl ethers ofbisphenols, with aliphatic polyols, the epoxy equivalent of saidcondensation products being at least 50,000, preferably 100,000, and inparticular between 100,000 and 400,000.

If BF₃ in the form of more stable complexes, for example complexed withamines, is used as specific catalysts (→c₂), the two components are usedto prepare the condensation products A(c) expediently in quantities suchthat the equivalent ratio of OH groups to epoxy groups is 1:1.8 to1:3.5, preferably 1:2.0 to 1:2.6. Suitable catalysts for this procedureare BF₃ -amine complexes which are soluble in the reaction mixture andin which the amine forming the complex has a pK_(b) value in aqueoussolution of 15 to 4.5. Suitable BF₃ -amine complexes are, for example,those which are formed from the following amines (pK_(b) values inbrackets) and BF₃ : n-amylamine (10.63), aniline (4.63),β-phenylalanine=2-amino ethyl benzene (9.84), 2-ethylbenzimidazole(6.18), benzylamine (9.33), transbornylamine (10.17),1-amino-3-methylbutane (10.60), 1.4-diaminobutane (11.15), n-butylamine(10.77), tert-butylamine (10.83), n-butylcyclohexylamine (11.23),cyclohexylamine (10.66), n-decylamine (10.64), diethylamine (10.49),diisobutylamine (10.91), diisopropylamine (10.96), dimethylamine(10.73), n-docecanamine=Laurylamine (10.63), 2-aminoethanol (9.50),ethylamine (10.81), hexadecanamine (10.63), 1-aminoheptene (10.66),2-aminoheptane (10.88), n-hexylamine (10.56), 2,4-dimethylimidazole(8.36), morpholine (8.33), methylamine (10.66), n-nonylamine (10.64),octadecanamine (10.60), octylamine (10.65), 3-aminopentane (10.59), 3-amino-3-methylpentane (11.01), n-pentadecylamine (10.61), piperazine(9.83), propylamine (10.71), pyrrolidine (11.27),tetradecanamine=myristylamine (10.62), tridecanamine (10.63),triethylamine (11.01), trimethylamine (9.81).

Preferably, BF₃ -benzylamine, BF₃ -monoethylamine, BF₃ -propylamine andBF₃ -n-butylamine are employed. Very suitable, however, are also BF₃-amine complexes converted to a liquid form by modification such as aremarketed, for example, by Anchor Chemical Ltd. (Manchester) under thedescription "Anchor" 1040 (containing 15-16% BF₃) or "Anchor" 1171(containing 11-12% BF₃).

The reaction of the hydroxyl groups with the epoxy groups can be carriedout in the temperature range from 20° to 200° C. The reactiontemperature is dependent on the BF₃ -amine complex concerned. Forexample, if BF₃ -monoethyl amine or BF₃ -benzylamine is used, thereaction temperature is 130° to 140° C., and if a liquefied aminecomplex is used, it is around 170° C. The mixtures of compoundscontaining hydroxyl groups and epoxy groups which are to be reacted aretherefore expediently heated to that temperature at which the reactionproceeds at an adequate rate, i.e. in 30 minutes to 15 hours. Thereaction is expediently tracked by means of the increase in the epoxyequivalent, which indicates a reduction in the epoxy groups. Thereaction can be terminated by cooling below the reaction temperature. Aportion of the BF₃ -amine complex is used up during the reaction byincorporation of the fluoride ions in the reaction product. Any excessof the BF₃ -amine complex can be rendered harmless after termination ofthe reaction by adding substances with a basic activity such asbleaching earth, calcium oxide, calcium hydroxide, barium oxide andbarium hydroxide to the complex in excess. The substances with basicactivity are removed together with the products produced from them andthe BF₃ -amine complexes by filtration.

The quantity of these catalysts is in general also 0.1 to 5, preferably0.15 to 1% by weight, referred to the reaction mixture. To improve thedosing, the catalyst may be diluted in a suitable solvent in an amountof up to 0.5 to 10, preferably 2.5 to 12.5% by weight.

Preferred condensation products (dispersants) A(c) produced using thesaid catalysts (c₂) are those of the epoxy compounds described above, inparticular polyglycidyl ethers of bisphenols, with aliphatic polyols,the epoxy equivalent of said condensation products being between 200 and120,000, preferably 400 and 10,000.

The quantity of condensation product A(c) in the self-emulsifying epoxyresin is in general about 3 to 15% by weight, preferably 4 to 9% byweight, referred to the self-emulsifying epoxy resin.

The quantity of water in the dispersion according to the invention isexpediently about 30 to 55% by weight, preferably about 35 to 50% byweight, referred to the total dispersion.

Suitable organic solvents corresponding to the component (C) of thedispersion according to the invention are, in particular, ethyleneglycol mono- or diethers, propylene glycol mono- or diethers, butyleneglycol mono- or diethers of monoalcohols with an optionally branchedalkyl radical containing 1 to 6 carbon atoms, aliphatic alcohols withoptionally branched alkyl radicals containing 1 to 12 carbon atoms,araliphatic and cycloaliphatic alcohols such as benzyl alcohol orcyclohexanol, aromatic compounds such as xylene, or ketones such asmethyl isobutyl ketones, it being possible to employ said solventsindividually or as mixtures. The boiling point of said solvents ispreferably not above 210° C. Preferred in this connection are ethylglycol, methyl glycol, methoxypropanol, ethoxypropanol and/or benzylalcohol. The epoxy resin dispersion according to the inventionpreferably contains about 2 to 15, in particular about 4 to 10% byweight of said organic solvents.

As normal additives in the sense of (D), which may optionally be presentin the combination according to the invention, mention may be made here,for example, of the normal lacquer additives such as pigments, pigmentpastes, antioxidants, leveling or thickening agents, defoaming agentsand/or wetting agents, reactive diluents, fillers, catalysts and thelike. Just like the hardeners and other thermosetting resins describedbelow, these additives may be added to the dispersion optionally onlyimmediately prior to processing.

As hardeners for the self-emulsifying epoxy resins of the invention, thehardeners or hardening compounds (epoxy hardeners) known for thispurpose, such as basic hardeners, (amine hardeners), for examplepolyamines, Mannich bases, adducts of amines on polymers such aspolyepoxides and polyamidoamines, may be employed. Furthermore, acidichardeners (acid hardeners) such as polycarboxylic acids and theiranhydrides, and also polyhydric phenols may be employed. Syntheticresins containing hydroxyl and/or amino groups, such as amine orphenolic resins, are also suitable for this purpose.

Examples of basic hardeners, preferably for hardening at roomtemperature or lower temperatures (amine cold hardeners), which are ingeneral employed in the epoxide equivalent:amine hydrogen equivalentratio of 1:(0.75 to 1.5), are polyalkylene amines such asdiethylenetriamine, triethylenetetramine, tetra-ethylenepentamine, etc.,and also 2,2,4- and/or 2,4,4-trimethylhexamethylenediamine,bis(3-aminopropyl)methylamine, 1,4-bis(3-aminopropyl)piperazine,N,N-bis(3-aminopropyl)ethylenediamine and also cycloaliphatic aminessuch as 1,2- or 1,3-diaminocyclohexane,1,4-diamino-3,6-diethylcyclohexane, 1,2-diamino-4-ethylcyclohexane,1,4-diamino-3,6-diethylcyclohexane,1,cyclohexyl-3,4-diamino-cyclohexane, isophoronediamine,4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylpropane,2,2-bis(4-aminocyclohexyl)propane,3,3'-dimethyl-4,4'-diamino-dicyclohexylmethane,3-amino-1-cyclohexaneaminopropane, 1,3- and1,4-bis(aminomethyl)cyclohexane.

As araliphatic amines, in particular those amines are employed in whichthe amino groups are present on the aliphatic radical for example m- andp-xylylenediamine or their hydrogenation products. The amines may beused alone or as mixtures.

Suitable Mannich bases are prepared by condensation of polyamines,preferably diethylenetriamine, triethylenetetramine, isophoronediamine,2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- and1,4-bis(aminomethyl)cyclohexane, in particular m- and p-xylylenediamine,with aldehydes, preferably formaldehyde and mono- or dihydric phenolscontaining at least one aldehyde-reactive nuclear position, for examplethe various cresols or xylenols, p-tert-butylphenol, resorcin,4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl-2,2-propane,preferably, however, phenol.

Suitable amine-epoxide adducts are, for example, reaction products ofdiamines such as, for example, ethylenediamine, propylenediamine,hexamethylenediamine, 2,2,4-, 2,4,4-trimethylhexamethylenediamine,m-xylylenediamine and/or bis(aminomethyl)cyclohexane with terminalepoxides such as, for example, propylene oxide, hexene oxide or withglycidyl ethers such as phenyl glycidyl ether, ethylhexyl glycidylether, butyl glycidyl ether or with glycidyl esters such as "Cardura E",or polyglycidyl ethers or esters such as are described under A(a) orA(c).

Polyamidoamines which can be used for the present purposes are obtained,for example by reacting polyamines with polycarboxylic acids such asdimerised fatty acids.

In addition to the above polyamines, the water-solublepolyoxypropylenediamines with molecular weights of 190 to 2,000 and alsothe readily water-dispersible hardeners, such as are described in theGerman Auslegeschrift 2,332,177 and the European Patent 0,000,605, i.e.,for example, modified amine adducts, are preferably employed as aminehardeners. To complete the full curing, the coatings obtainable fromthese dispersions may also be heated for 30 to 120 minutes at 50° to120° C.

Suitable acidic hardeners, which are usually used in an epoxy: carboxylequivalent ratio of 1:(0.75 to 1.5) are water soluble polycarboxylicacids, for example cyclopentanetetracarboxylic acid, in particularbutanetetracarboxylic acids such as cyclobutanetetracarboxylic acid,preferably 1,2,3,4-butanetetracarboxylic acid, and also aconitic acid,citric acid or optionally anhydrides or acid esters of said acids withpolyhydric alcohols containing 2 to 12, preferably 2 to 6 carbon atomssuch as neopentyl glycol, glycerol, trimethylolethane or -propane, thealkane diols and their oligomers, which optionally contain one or moreether bridges, such as ethylene glycol, propane- and butanediols, theesters always having at least 3 free COOH groups. It is also possible touse acid esters containing three or more COOH groups of pyromelliticacid, trimellitic acid, phthalic acid, endomethylenetetra- or-hexahydrophthalic acid, maleic acid, fumaric acid or their anhydrides,insofar as they exist, with polyhydric alcohols, for example thosementioned above, as polycarboxylic acid hardeners, insofar as saidacidic esters have an adequate water solubility or water dilutability.In this connection it should be noted that dibasic carboxylic acids arereacted with at least trihydric alcohols or dihydric alcohols with atleast tribasic acids in order to achieve an adequate number of COOHgroups in the acidic esters.

Instead of or in addition to the hardeners described above, amine and/orphenolic resins in quantities of 5 to 50% by weight, preferably 10 to35% by weight, referred to the total solids content, may also be usedfor curing. Optionally, water is also additionally added to thedispersion at the same time so that the total solids content is adjustedto 10 to 80% by weight. Examples of such amine resins are aminealdehyderesins, i.e. condensation products of aldehydes with melamine (melamineresins), urea (urea resins), acetoguanamine (acetoguanamine resins) orsimilar compounds or corresponding precondensates. Preferred aldehydecondensation products of melamine are, in particular, the melaminemethylol alkyl ethers, the alkyl radicals being composed of methyl, n-or i-butyl groups preferably methyl groups, such ashexamethoxymethylmelamine, ethoxymethoxymethylmelamine,monomethylolpentamethoxymethylenemelamine,dimethyloltetramethoxymethylenemelamine,trimethyloltrimethoxymethylenemelamine and the like, with substantiallymonomeric structure, and also corresponding oligomers or polymericproducts.

As phenolic resin hardeners mention may be made of resols, formalde-hydephenolcarboxylic acid resins and phenolic resin intermediates, thecommercial etherified, water-dilutable phenolic resin resols beingpreferred. Optionally, acidic catalysts such as p-toluene sulfonic acid,cyclohexanesulfamine acid, acidic butylphosphate and phosphoricacid--optionally also as (amine) salts--may also be added to thedispersions containing phenolic and/or amine resin in order to increasethe rate of the curing reaction so that films or coatings are producedwhich cure at fairly low temperature or in a fairly short time. Thequantity of said acid catalysts is, for example, up to 2% by weight,referred to the total solids content.

Additional hardenable resins in the sense of the component (D) are, forexample, resins dispersible in aqueous media based on hydroxyalkylacrylates, hydroxyalkydes, polyesters, epoxy resins and the like. Theproportion of said additional resins may, for example, be so dimensionedthat the total solids content of the mixture is about 10 to 80,preferably 20 to 40% by weight. By adding such resins the properties ofthe products prepared from the dispersions can be influenced in adesired manner. Thus, for example, it is possible to improve theresistance to yellowing of the coatings prepared therefrom by thepresence of acylate resins and the elasticity by adding alkyd resins.

The total solids content of the epoxy resin dispersion according to theinvention may be between about 10 and 80% by weight and is expediently35 to 70% by weight, preferably 45 to 60% by weight; its viscosity is ingeneral between 300 and 30,000 mPa.s, preferably between 1,000 and 7,000mPa.s (20° C.). The epoxy resin dispersion according to the invention isremarkable, in particular, for its good storage stability, due mainly tothe low mean particle size of the self-emuslifying epoxy resin with acontent of organic solvents which is also low. The coatings obtainablewith this dispersion have, in addition, a reduced sensitivity to water,with improved hardness.

In the process according to the invention for the preparation of saidepoxy resin dispersions, the self-emulsifying epoxy resin (A) is firstprepared by condensation of the three components A(a), A(b) and A(c) atelevated temperatures, in general 120° to 220° C., preferably 150° to180° C., in the presence of a condensation catalyst. Suitable as thelatter are, for example, phosphines such as triphenylphosphine,phosphonium salts such as, for example, benzyltrimethylphosphoniumchloride, tertiary amines such as, for example, benzyldimethylamine,quaternary ammonium salts such as, for example, tetramethylammoniumchloride, alkali-metal hydroxides such as NaOH, LiOH, alkali-metalcarbonates such as sodium carbonate, lithium carbonate, alkali-metalsalts of organic acids such as sodium formate and lithium benzoate. Theorganic solvent (C) may also be already fully or partially presentduring this condensation.

Subsequently the organic solvent (insofar as the condensation has notalready taken place in the presence of the total quantity of the organicsolvent) is added to said resin at temperatures of 120° C. to 220° C.,preferably 100° to 160° C. and a solution is produced. Then theappropriate quantity of water is added while stirring vigorously attemperatures of 30° to 100° C., preferably 55° to 75° C., as a result ofwhich the aqueous dispersion is produced. This dispersion is expedientlycarried out using a fast-running paddle stirrer, a colloid mill, ahomogenizer or another fast mixer with high shearing force, for examplea dissolver.

The compounds corresponding to D (additives, hardeners, otherthermosetting resins) are preferably added only immediately before thedispersion is used.

The dispersions according to the invention are suitable in conjunctionwith suitable hardeners mainly for preparing coatings and/orintermediate coatings for the most diverse fields of application, inparticular as protective coatings on rough and porous substrates. Theyare further suitable for chemical- and weathering-resistant coatings andlinings of objects.

Owing to their beneficial properties, the dispersions according to theinvention are also outstandingly suitable for single-layer lacquering.The adhesive coating layer may remain unaltered, but it may also serveas an intermediate layer, i.e. as a base for further coatings, which mayin turn be composed of the same or a different normal coating material.

Because of their good dilutability and their other beneficialproperties, the dispersions according to the invention are also suitablefor additional use in electrophoretic painting.

A further possibility is their use for water-dilutable adhesives. Theymay also be employed as binders for textiles, and organic and/orinorganic materials. They are also suitable for use as thermosettingmolding compounds. In addition, they can also serve as an additive forsynthetic cements.

In the event of being used as a coating agent (or as a predominantlyaqueous lacquer, the deposition on the substrate such as metal, wood,glass, concrete, plastic, ceramic etc., is carried out by conventionalmethods such as brushing, spraying, dipping or rolling on. Insofar as nohardener is also used for cold curing, the coatings are cured by heatingto 100° to 250° C. for a time sufficient for curing, in general aboutfive minutes to one hour.

In the experiments and examples below, % means in all cases percent byweight. The viscosity was always measured at room temperature with aBrookfield viscometer.

EXAMPLES

I. Preparation of the condensation products (dispersants) A(c) withcatalyst c₁)

In all the examples 1 to 9, the reaction mixture was heated to 130° C.after adding the BF₃ compound and kept at this temperature until thereaction had finished, which was indicated by an increase in the epoxyequivalent to the specified value in each case.

(1) 150 g of technical polyethylene glycol having a mean molecularweight (Mw) of 3,000 and 18.5 g of a polyglycidyl ether based onbisphenol A having an epoxy equivalent of 185 were heated together to100° C. and 0.9 g of BF₃ -etherate, diluted to 5% by weight withdioxane, was added while stirring. The OH/epoxy equivalent ratio was1:1, the epoxy equivalent was approx. 360,000.

(2) 200 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 18.5 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and0.9 g of BF₃ -etherate was added while stirring. The OH/epoxy equivalentratio was 1:1, the epoxy equivalent was approx. 70,000.

(3) 200 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 18.5 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and0.9 g of BF₃ -etherate, diluted to 5% by weight with diethyl ether wasadded while stirring. The OH/epoxy equivalent ratio was 1:1, the epoxyequivalent was approx. 200,000.

(4) 200 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 23.0 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and0.9 g of BF₃ -etherate, diluted with dioxane to 5% by weight, was addedwhile stirring. The OH/epoxy equivalent ratio was 1:1.25, the epoxyequivalent was approx. 250,000.

(5) 200 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 13.80 g of a polyglycidyl ether based on bisphenol Awith an epoxy equivalent of 185 were heated together to 100° C. and 0.9g of BF₃ -etherate, diluted to 5% by weight with dioxane, was addedwhile stirring. The OH/epoxy equivalent ratio was 1:0.75, the epoxyequivalent was approx. 270,000.

(6) 200 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 18.5 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and1.2 g of BF₃ -acetic acid, diluted to 5% by weight with ethylene glycolmonoethyl ether, were added while stirring. The OH/epoxy equivalentratio was 1:1, the epoxy equivalent was approximately 150,000.

(7) 300 g of technical polyethylene glycol having a mean molecularweight of 6,000 and 18.5 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and1.2 g of BF₃ -etherate, diluted to 5% by weight with dioxane, were addedwhile stirring. The OH/epoxy equivalent ratio was 1:1, the epoxyequivalent was approx. 170,000.

(8) 200 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 25.0 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 250 were heated together to 100° C. and1.2 g of BF₃ -etherate, diluted to 5% by weight with dioxane, were addedwhile stirring. The OH/epoxy equivalent ratio was 1:1, the epoxyequivalent was approx. 180,000. (9) 200 g of technical polyethyleneglycol having a mean molecular weight of 4,000 and 45.0 g of apolyglycidyl ether based on bisphenol A having an epoxy equivalent of450 were heated together to 100° C. and 2.0 g of BF₃ -etherate, dilutedto 5% by weight with dioxane, were added while stirring. The OH/epoxyequivalent ratio was 1:1, the epoxy equivalent was approx. 230,000.

(10) 300 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 34.4 g of a polyglycidyl ether based onpolyoxypropylene glycol (n=4) having an epoxy equivalent of 199 wereheated together to 100° C. and 0.7 g of BF₃ -etherate, diluted with 10ml of methyl isobutyl ketone, was added while stirring. The OH/epoxyequivalent ratio was 1:1.15, the epoxy equivalent of the condensate wasapprox. 150,000.

(11) 300 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 55.2 g of a polyglycidyl ether based on apolyoxypropylene glycol (n=9) having an epoxy equivalent of 320 wereheated together to 100° C. and 0.7 g of BF₃ -etherate, diluted with 10ml of methyl isobutyl ketone, were added while stirring. The OH/epoxyequivalent ratio was 1:1.15, the epoxy equivalent of the condensate wasapprox. 130,000.

(12) 300 g of technical polyethylene glycol with a mean molecular weightof 4,000 and 31.9 g of a polyglycidyl ether based on bisphenol A havingan epoxy equivalent of 185 were heated together to 100° C. and 1.0 g ofBF₃ -etherate, diluted with 10 ml of methyl isobutyl ketone, was addedwhile stirring. The OH/epoxy equivalent ratio was 1:1.15, the epoxyequivalent of the condensate was approx. 150,000.

(13) 150 g of technical polyethylene glycol having a mean molecularweight of 4,000, 150 g of a copolymer of ethylene oxide and propyleneoxide having a content of 80% by weight of ethylene oxide and a meanmolecular weight of 8,000 and 23.7 g of a polyglycidyl ether based onbisphenol A having an epoxy equivalent of 185 were heated together to100° C. and 0.9 g of BF₃ -etherate, diluted with 10 ml of methylisobutyl ketone, was added while stirring. The OH/epoxy equivalent ratiowas 1:1.15, the epoxy equivalent of the condensate was approx. 120,000.

(14) 309 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 32.5 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and0.5 ml of BF₃ -dihydrate, diluted with 10 ml of methyl isobutyl ketone,was added while stirring. The OH/epoxy equivalent ratio was 1:1.15, theepoxy equivalent of the condensate was approx. 20,000.

(15) 309 g of technical polyethylene glycol having a mean molecularweight of 4,000 and 32.5 g of a polyglycidyl ether based on bisphenol Ahaving an epoxy equivalent of 185 were heated together to 100° C. and0.5 ml of HBF₄, 50% solution in H₂ O, diluted with 10 ml ofmethylisobutyl ketone, was added while stirring. The OH/epoxy equivalentratio was 1:1.15, the epoxy equivalent of the condensate was approx.350,000.

II. Preparation of the condensation product (dispersant) A(c) using thecatalysts mentioned under 2).

(1) 500 g of a polyethylene glycol with a mean molecular weight of 4,000and 92.5 g of a polyglycidyl ether based on bisphenol A having an epoxyequivalent of 185 were heated together to 120° C. 1.5 g of the BF₃-amine complex "Anchor" 1040 were added and heated to 170° C. The epoxyequivalent was checked. A further 2 g of the amine complex "Anchor" 1040were added in two batches. After the theoretical epoxy equivalent of2,320, which is equivalent to the reaction of the hydroxyl groups of thepolyethylene glycol, had been reached, the reaction was terminated. A50% by weight solution of the condensation product in benzyl alcohol hada viscosity of 555 mPa.s (25° C.). The epoxy equivalent was 2,360 andthe OH/epoxy equivalent ratio was 1:2.0.

(2) 500 g of a polyethylene glycol having a mean molecular weight of4,000 and 115.5 g of a polyglycidyl ether based on bisphenol A having anepoxy equivalent of 185 were heated together to 120° C. 2g of the BF₃-amine complex "Anchor" 1040 were added and heated to 170° C. The epoxyequivalent was checked. A further 0.85 g of the amine complex "Anchor"1040 was added in three batches. After the epoxy equivalent of 1,940,which signifies a 20% higher condensation of the coreactant than isequivalent to the reaction of the hydroxyl groups of the polyethyleneglycol, had been reached, the reaction was terminated. The OH/epoxyequivalent ratio was 1:2.5.

(3) 500 g of a polyethylene glycol having a mean molecular weight of4,000 and 92.5 g of a polyglycidyl ether based on bisphenol A having anepoxy equivalent of 185 were heated together to 120° C. 2 g of BF₃-monoethylamine were added and heated to 150° C. The epoxy equivalentwas checked. After the epoxy equivalent of 3,140, which signifies a 25%higher condensation of the coreactant than is equivalent to the reactionof the hydroxyl groups of the polyethylene glycol, had been reached, thereaction was terminated. The OH/epoxy equivalent ratio was 1:2.0.

III. Examples of the preparation of the dispersion according to theinvention using the condensation products as in the Examples I. 1-15.

(1) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A having an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant I. (1) in the presence of750 mg of triphenylphosphine at 150° to 160° C. until an epoxyequivalent of 490-500 was reached. Dilution was then carried out whilecooling with 27 g of benzyl alcohol and 60 g of methoxypropanol. 105 gof deionzied water were added steadily in a time period of 5-30 min. ata stirring speed of approximately 800 revolutions per minute and with areduction of the temperature to 70°-60° C., an aqueous dispersion beingproduced which was subsequently diluted further with 173 g of deionizedwater. The dispersion had a solids content of 55.7% by weight, aviscosity of 11,700 mPa.s (Brookfield, spindle 3 at 6 rpm) and also aparticle size of 0.66 μm.

(2) In a 2 L 3-necked flask equipped with thermometer, paddle stirrer,reflux condenser and dropping funnel, 325 g of an epoxy resin based onbisphenol A with an epoxy equivalent of 183 were reacted with 98 g ofbisphenol A and 27 g of the dispersant (I.2) dissolved in 27 g of benzylalcohol in the presence of 750 mg of triphenylphosphine at 150° to 160°C. until an epoxy equivalent of 530-550 was reached. Dilution wascarried out while cooling with 60 g of methoxypropanol. 105 g ofdeionized water were added steadily in a time period of 5-30 min. at astirring speed of approximately 800 revolutions per minute and with areduction of the temperature to 70°-60° C., an aqueous dispersion beingproduced which was subsequently diluted further with 180 g of deionizedwater. The dispersion had a solids content of 54.5% by weight, aviscosity of 6,700 mPa.s (Brookfield, spindle 3 at 6 rpm) and also aparticle size of 0.60 μm.

(3) In a 2 L 3-necked flask equipped with thermometer, paddle stirrer,reflux condenser and dropping funnel, 325 g of an epoxy resin based onbisphenol A with an epoxy equivalent of 183 were reacted with 120 g ofbisphenol A and 27 g of the dispersant (I.3) dissolved in 27 g of benzylalcohol in the presence of 700 mg triphenylphosphine at 150° to 160° C.until an epoxy equivalent of 690-720 was reached. Dilution was carriedout whilst cooling with 60 g of methoxypropanol. 100 g of deionizedwater were added steadily in a time period of 5-30 min. at a stirringspeed of approximately 800 revolutions per minute and with a reductionin the temperature to 70°-60° C., an aqueous dispersion being producedwhich was subsequently diluted further with 230 g of deionized water.The dispersion had a solids content of 53.5% by weight, a viscosity of7,600 mPa.s (Brookfield, spindle 3 at 6 rpm) and also a particle size of6.76 μm.

(4) The procedure was in accordance with the directions of Example(II.2). However, ethoxypropanol was employed instead of methoxypropanol.

The dispersion obtained had a solids content of 54.3% by weight, aviscosity of 8,300 mPa.s (Brookfield, spindle 3 at 6 rpm) and also aparticle size of 0.75 μm.

(5) Example (II.2) was repeated; however, ethyl glycol was employedinstead of methoxypropanol. The dispersion had a solids content of 54.0%by weight, a viscosity of 4,500 mPa.s (Brookfield, spindle 3 at 6 rpm)and also a particle size of 0.61 μm.

(6) Example (II.2) was repeated; however, butyl diglycol was employedinstead of methoxypropanol. The dispersion obtained had a solids contentof 55.0% by weight, a viscosity of 12,200 mPa.s (Brookfield, spindle 3at 6 rpm) and also a particle size of 0.72 μm.

(7) The procedure was as in Example (II.2); however, 45 g ofmethoxypropanol was employed instead of 60 g and dilution was carriedout with an additional 15 g of deionized water. The dispersion obtainedhad a solids content of 53.9% by weight, a viscosity of 6,500 mPa.s(Brookfield, spindle 3 at 6 rpm) and also a particle size of 0.66 μm.

(8) The procedure was as in Example (II.2); however, the dispersant I.4was employed instead of the dispersant I.1. The dispersion obtained hada solids content of 53.9% by weight, a viscosity of 5,800 mPa.s(Brookfield, spindle 3 at 6 rpm) and also a particle size of 0.63 μm.

(9) The procedure was as in Example (II.2); however, the dispersant I.7was employed instead of the dispersant I.2. The dispersion had a solidscontent of 55.4% by weight, a viscosity of 4,900 mPa.s (Brookfield,spindle 3 at 6 rpm) and also a particle size of 0.59 μm.

(10) In a 2 L three-neck flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 was reacted with 98g of bisphenol A and 27 g of the dispersant (I.12) dissolved in 27 g ofbenzyl alcohol in the presence of triphenylphosphine at 150° to 160° C.until an epoxy equivalent of 530 was reached. Dilution was carried outwhile cooling with 60 g of methoxypropanol. 85 g of deionized water wereadded and stirred in a time period of 5 min. below a temperature of 70°C. at a stirring speed of approx. 800 revolutions per minute, an aqueousdispersion being produced which was subsequently diluted further with230 g of deionized water. The dispersion had a solids content of 52.9%by weight, a viscosity of 3,900 mPa.s (Brookfield, spindle 2 at 6 rpm)and also a particle size of 0.50 μm.

(11) In a 2 L three-neck flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (I.12) dissolved in 27 gof benzyl alcohol in the presence of 600 mg triphenylphosphine at 150°to 160° C. until an epoxy equivalent of 530 was reached. Dilution wascarried out while cooling with 30 g of methoxypropanol and 30 g ofn-hexylglycol. 85 g of deionized water were added and stirred in a timeperiod of 5 min. below a temperature of 70° C. at a stirring speed ofapprox. 800 revolutions per minute, an aqueous dispersion being producedwhich was subsequently diluted further with 230 g of deionized water.The dispersion had a solids content of 53.0% by weight, a viscosity of4,700 mPa.s (Brookfield, spindle 2 at 6 rpm) and also a particle size of0.58 μm.

(12) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (I.12) dissolved in 27 gof benzyl alcohol in the presence of 700 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of 530 was reached. Dilutionwas carried out while cooling with 30 g of methoxypropanol and 30 g ofbutyl glycol. 90 g of deionized water were added and stirred in a timeperiod of 5 min. below a temperature of 70° C. at a stirring speed ofapproximately 800 revolutions per minute, an aqueous dispersion beingproduced which was subsequently diluted further with 220 g of deionizedwater. The dispersion had a solids content of 53.0% by weight, aviscosity of 3,400 mPa.s (Brookfield, spindle 3 at 6 rpm) and also aparticle size of 0.54 μm.

(13) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (I.10) dissolved in 27 gof benzyl alcohol in the presence of 750 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of approximately 535 wasreached. Dilution was carried out while cooling with 60 g ofmethoxypropanol. 140 g of deionized water were added in a time period of20 min. below a temperature of 70° C. at a stirring speed of approx. 800revolutions per minute, an aqueous dispersion being produced which wassubsequently diluted further with 170 g of deionized water. Thedispersion had a solids content of 53.2% by weight, a viscosity of 260mPa.s (Brookfield spindle 3 at 12 rpm) and also a particle size of 0.80μm.

(14) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (I.11) dissolved in 27 gof benzyl alcohol in the presence of 750 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of approximately 535 wasreached. Dilution was carried out while cooling with 60 g ofmethoxypropanol. 165 g of deionized water were added in a period of 25min. below a temperature of 70° C. and at a stirring speed ofapproximately 800 revolutions per minute, an aqueous dispersion beingproduced which was subsequently diluted further with 155 g of deionizedwater. The dispersion had a solids content of 53.2% by weight, aviscosity of 670 mPa.s (Brookfield, spindle 2 at 30 rpm) and also aparticle size of 0.79 μm.

(15) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (I.13) dissolved in 27 gof benzyl alcohol in the presence of 750 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of approximately 530 wasreached. Dilution was carried out while cooling with 60 g ofmethoxypropanol. 185 g of deionized water were added and stirred in atime period of 5 min. below a temperature of 70° C. at a stirring speedof approximately 800 revolutions per minute, an aqueous dispersion beingproduced which was subsequently diluted further with 290 g of deionizedwater. The dispersion had a solids content of 52.5% by weight, aviscosity of 760 mPa.s (Brookfield, spindle 2 at 12 rpm) and also aparticle size of 0.45 μm.

IV. Examples of the preparation of the dispersions according to theinvention using the condensation products of Examples II.1 to 3.

(1) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (II.1) dissolved in 27 gof benzyl alcohol in the presence of 600 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of approximately 500 wasreached. Dilution was carried out while cooling with 60 g ofmethoxypropanol. 85 g of deionized water were added and stirred in atime period of 5 min. below a temperature of 70° C. at a stirring speedof approximately 800 revolutions per minute, an aqueous dispersion beingproduced which was subsequently diluted further with 235 g of deionizedwater. The dispersion had a solids content of 53.0% by weight, aviscosity of 150 mPa.s (Brookfield, spindle 2 at 30 rpm) and also aparticle size of 0.80 μm.

(2) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 54 g of the dispersant (II.1) dissolved in 54 gof benzyl alcohol in the presence of 600 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of approximately 550 wasreached. Dilution was carried out while cooling with 33 g ofmethoxypropanol. 85 g of deionized water were added and stirred in atime period of 5 min. below a temperature of 70° C. at a stirring speedof approx. 800 revolutions per minute, an aqueous dispersion beingproduced which was subsequently diluted further with 230 g of deionizedwater. Diluted to a solids content of 52.5% by weight, the dispersionhad a viscosity of 3,000 mPa.s (Brookfield, spindle 2 at 12 rpm) andalso a particle size of 0.60 μm.

(3) In a 2 1 three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 was reacted with 98g of bisphenol A and 54 g of the dispersant (II.1) dissolved in 27 g ofbenzyl alcohol in the presence of 600 mg of triphenylphosphine at 150°to 160° C. until an epoxy equivalent of approximately 530 was reached.Dilution was carried out while cooling with 60 g of methoxypropanol. 85g of deionized water were added and stirred in a time period of 5 min.below a temperature of 70° C. at a stirring speed of approximately 800revolutions per minute, an aqueous dispersion being produced which wassubsequently diluted further with 245 g of deionized water. Thedispersion had a solids content of 53.0% by weight, a viscosity of 2,400mPa.s (Brookfield spindle 3 at 12 rpm) and also a particle size of 0.40μm.

(4) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 27 g of the dispersant (II.2) dissolved in 27 gof benzyl alcohol in the presence of 750 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of 510 was reached. Dilutionwas carried out while cooling with 60 g of methoxypropanol. 85 g ofdeionized water were added and stirred in a time period of 5 min. belowa temperature of 70° C. at a stirring speed of approx. 800 revolutionsper minute, an aqueous dispersion being produced which was subsequentlydiluted further with 205 g of deionized water. Diluted to a solidscontent of 54.9% by weight, the dispersion had a viscosity of 625 mPa.s(Brookfield, spindle 2 at 12 rpm) and also a particle size of 0.55 μm.

(5) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 182 were reacted with98 g of bisphenol A and 42 g of the dispersant (II.2) dissolved in 27 gof benzyl alcohol in the presence of 750 mg of triphenylphosphine at150° to 160° C. until an epoxy equivalent of approximately 520 wasreached. Dilution was carried out while cooling with 60 g ofmethoxypropanol. 85 g of deionized water were added and stirred in atime period of 5 min. below a temperature of 70° C. at a stirring speedof approximately 800 revolutions per minute, an aqueous dispersion beingproduced which was subsequently diluted further with 230 g of deionizedwater. With a solids content of 5.41% by weight, the dispersion had aviscosity of 2,500 mPa.s (Brookfield, spindle 2 at 6 rpm) and also aparticle size of 0.52 μm.

(6) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel 325 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with98 g of bisphenol A and 42 g of the dispersant (II.3) dissolved in 27 gof benzyl alcohol in the presence of 600 mg of triphenyphosphine at150°-160° C. until an epoxy equivalent of 515 was reached. Dilution wascarried out while cooling with 60 g of methoxypropanol. 85 g ofdeionized water were added and stirred in a time period of 5 minutesbelow a temperature of 70° C. at a stirring speed of approx. 800revolutions per minute, an aqueous dispersion being produced which wassubsequently diluted further with 235 g of deionized water. At a solidscontent of 53.8% by weight, the dispersion had a viscosity of 1,250mPa.s (Brookfield, spindle 2 at 12 rpm) and also a particle size of 0.43μm.

(7) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 295 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 182 were reacted with128 g of bisphenol A, 42 g of the dispersant (II.3) and 27 g of benzylalcohol in the presence of 600 mg of triphenylphosphine at 150° to 165°C. until an epoxy equivalent of approx. 1,000 was reached. Dilution wascarried out while stirring with 60 g of methoxy propanol. 85 g ofdeionized water were added and stirred in a time period of 5 min. belowa temperature of 70° C. at a stirring speed of approximately 800revolutions per minute, an aqueous dispersion being produced which wassubsequently diluted further with 280 g of deionized water. Thedispersion had a solids content of 51.1% by weight, a viscosity of 3,700mPa.s (Brookfield, spindle 3 at 12 rpm) and also a particle size of 0.57μm.

(8) In a 2 L three-necked flask equipped with thermometer, paddlestirrer, reflux condenser and dropping funnel, 281 g of an epoxy resinbased on bisphenol A with an epoxy equivalent of 183 were reacted with142 g of bisphenol A and 27 g of the dispersant (II.3) in the presenceof 650 mg of triphenylphosphine at 150° to 165° C. until an epoxyequivalent of approximately 1,500 was reached. Dilution was carried outwhile cooling with 60 g of methoxypropanol and 120 g of isopropanol. 75g of deionized water were added and stirred in a time period of 5minutes below a temperature of 70° C. at a stirring speed of approx. 800revolutions per minute, an aqueous dispersion being produced which wassubsequently diluted further with 400 g of deionized water. Isopropanoland a portion of the water were removed again under a reduced pressureof approximately 25 mm of Hg and a temperature of < 40° C. Thedispersion had a solids content of 50.3% by weight, a viscosity of 1,000mPa.s (Brookfield, spindle 2 at 12 rpm) and also a particle size of 0.70μm.

V. Application engineering tests

A dispersion according to the invention (→ Example II.2) and also adispersion in accordance with the prior art (European Patent 81,163)were subjected to a series of application engineering tests. The resultsare shown in the two tables 1 and 2 below.

                  TABLE 1                                                         ______________________________________                                                             Comparison                                                            According to                                                                            (Dispersion                                                         the invention                                                                           according to                                                        (Example III.2)                                                                          EP 81,163, Ex. 2)                                     ______________________________________                                        Dispersion     100     parts   100    parts                                   Hardener acc. to                                                                             20      parts   20                                             Eur. P. 0,000,605, Ex. 5c                                                     Dry to the touch (RT)                                                                        50      min     110    min                                     Tack-free (RT) 105     min     175    min                                     Pendulum hardness (24h)                                                                      69      s       26     s                                       Pendulum hardness (7d)                                                                       135     s       80     s                                       Film clouding after                                                                          4       h       3.5    h                                       Water-resistance                                                                             1               3                                              after 24 h storage                                                            ______________________________________                                         1. Dry to the touch: glass beads scattered on the film can no longer be       removed with a paintbrush after curing.                                       2. Tackfree: The glass beads can be removed with a paintbrush after           curing.                                                                       3. Konig pendulum hardness: DIN 53 157                                        4. Film clouding: After mixing dispersion and hardener, films are applied     every half hour to glass plates in a layer thickness of 200 μm. The        appearance of a clouding                                                      in the film is the result of the test and also the end of the processing      time.                                                                         5. Water resistance after 24 h storage at room temp.: Films applied to        glass plates with a layer thickness of 200 μm are tested after storing     for 24 h in H.sub.2 O at room temperature. Scale: 0 = very good, 5 = poor

                  TABLE 2                                                         ______________________________________                                        (testing of the gloss stability)                                                                     Comparison                                                          According to                                                                  the invention                                                                           according to                                                        (Example III.12)                                                                        EP 81,163, Ex. 2.)                                     ______________________________________                                        Dispersion     100     parts   100    parts                                   TiO.sub.2      35.4    parts   32.5   parts                                   Hexamethoxymethyl-                                                                           0.7     parts   0.65   parts                                   melamine                                                                      H.sub.2 O      33      parts   25                                             Hardener acc. to                                                                             20.6    parts   19.0   parts                                   Eur. P. 0,000,605, Ex. 5c                                                     Gloss stability*                                                              immediately    99              65                                             30 min.        100             67                                             1 h            99              67                                             2 h            94              58                                             3 h            86              45                                             4 h            45              33                                             5 h            29              --                                             ______________________________________                                         *as specified in DIN 67 530; 60°                                  

We claim:
 1. An aqueous dispersion comprising a self-emulsifying epoxyresin (A), wherein the self-emulsifying epoxy resin (A) has an epoxyequivalent of between 250 and 10,000 and a mean particle size of 0.25 to1.0 μm and is a condensation product of(a) 50 to 80% by weight of anepoxy compound containing at least two epoxy groups per molecule andhaving an epoxy equivalent of 100 to 2,000, (b) 35 to 17% by weight ofan polyhydric phenol and (c) 15 to 3% by weight of a condensationproduct of an aliphatic polyol with a mean molecular weight (Mw) of 200to 20,000 and an epoxy compound containing at least two epoxy groups permolecule and having an epoxy equivalent of 100 to 2,000, the equivalentratio of the OH groups to the epoxy groups being 1:0.95 to 1:3.5 and theepoxy equivalent of said condensation product being between 200 and atleast 50,000.
 2. An epoxy resin dispersion as claimed in claim 1,wherein the quantity of the self-emulsifying epoxy resin is 30 to 70% byweight, referred to the total dispersion, and the epoxy equivalent is450 to 2,500.
 3. An epoxy resin dispersion as claimed in claim 1,wherein the epoxy compounds corresponding to A(a) and A(c) are at leastone member of the group consisting of polyglycidyl ethers andpolyglycidyl esters based on polyhydric phenols and novolaks.
 4. Anepoxy resin dispersion as claimed in claim 3, wherein the polyhydricphenol is bisphenol A.
 5. An epoxy resin dispersion as claimed in claim3, wherein the epoxy compounds have epoxy equivalents of 170 to 1,000.6. An epoxy resin dispersion as claimed in claim 1, wherein thealiphatic polyol corresponding to A(c) is polyalkylene glycol having amolecular weight (Mw) of 600 to 12,000.
 7. An epoxy resin dispersion asclaimed in claim 1, wherein the quantity of A(c) is 4 to 9% by weight,referred to the total self-emulsifying epoxy resin.
 8. Epoxy resindispersion as claimed in claim 1, wherein, in the condensation product(c), the equivalent ratio of the OH groups to the epoxy groups is either(c₁) 1:0.85 to 1:1.5 and the epoxy equivalent is at least 100,000 or(c₂) the equivalent ratio is 1:1.8 to 1:3.5 and the epoxy equivalent is400 to 10,000.
 9. An epoxy resin dispersion as claimed in claim 1,wherein the quantity of water is 30 to 55% by weight.
 10. An epoxy resindispersion as claimed in claim 1, wherein it contains up to 15% byweight, referred to the total dispersion, of organic solvents.
 11. Anepoxy resin dispersion as claimed in claim 10, wherein the quantity oforganic solvents is 2 to 15% by weight.
 12. An epoxy resin dispersion asclaimed in claim 11, wherein ethylene glycol mono- or diethers,propylene glycol mono- or diethers, butylene glycol mono- or diethers ofmonoalcohols having an branched or unbranched alkyl radicalscontaining 1to 6 carbon atoms, aliphatic alcohols having unbranched or branchedalkyl radicals containing 1 to 12 carbon atoms, araliphatic andcycloaliphatic alcohols, aromatic compounds or ketones are employedindividually or as a mixture as organic solvents.
 13. An epoxy resindispersion as claimed in claim 1, wherein it contains additionalconstituents (D) from the group comprising normal additives, hardenersand other thermosetting resins.
 14. An epoxy resin dispersion as claimedin claim 13, characterized in that basic or acidic hardeners serve ashardeners.
 15. An epoxy resin dispersion as claimed in claim 14, whereinbase hardeners are polyoxypropylene amines, polyglycidyl ether/amineadducts or polyamidoamines, said amine hardeners being used in an epoxyequivalent ratio of 1: (0.75 to 1.5).
 16. Epoxy resin dispersion asclaimed in claim 15, wherein amine and/or phenolic resins are employedas further thermosetting resins.
 17. An epoxy resin dispersion asclaimed in claim 1, wherein the mean particle size of theself-emulsifying epoxy resin is 0.25 to 0.8 μm.
 18. A process for thepreparation of the epoxy resin dispersion as claimed in claim 1 whereinself-emulsifying epoxy resin (A) is first prepared by condensation ofthe three components A(a), A(b) and A(c) at elevated temperatures in thepresence of a condensation catalyst and then appropriate quantities ofwater are added at 30° to 100° C. with vigorous stirring to the solutionthus obtained.
 19. The process as claimed in claim 18 wherein thecondensation is carried out at temperatures of 120° to 220° C.
 20. Theprocess as claimed in claim 18, wherein the addition of the compoundscorresponding to (D) is carried out only immediately before use. 21.Painting materials, coatings, molding compounds and thermosettingmaterials containing the epoxy resin dispersion of claim
 1. 22. Theprocess as claimed in claim 18 wherein the condensation is carried outin the presence of at least one organic solvent.
 23. The process asclaimed in claim 22, wherein at least one organic solvent is furtheradded to the resin (A) subsequent to the condensation reaction.
 24. Theprocess as claimed in claim 23, wherein the total quantity of organicsolvent is up to 15% by weight, calculated on the total dispersion. 25.The process as claimed in claim 18, wherein compounds of the groupconsisting of additives, hardeners and other thermosetting resins, areadded to the epoxy resin dispersion.
 26. The process as claimed in claim25 wherein the said compounds are added only immediately before use.